Microwave Plasma Generation And Exploration In Application Of Methane Reforming To Produce Hydrogen

In recent years, microwave plasma technology has attracted more and more attention of the researchers. Because of its high ionization, high electron temperature, high electron density, wide pressure scope, no pole and no pollution, etc, microwave plasma is widely used in plasma surface treatment, thin films, chemical vapor deposition, etching technology and reforming methane to produce hydrogen etc. It is different from DC discharge, AC discharge or high-frequency discharge, in microwave discharge, the energy must be transmitted by waveguide not the normal circuit and be coupled into the reactor to produce plasma. However, it is not mature to transfer and couple microwave energy into the reactor efficiently, and it is known not enough of the characteristics of microwave plasma, especially lack of kilowatt microwave plasma chemical experimental plat. So the development of the application of microwave plasma in chemical technology is seriously hindered. Therefore, it is very necessary to establish a high-power microwave plasma generation platform to research the microwave plasma discharge characteristics and the application of the technology.Base on electromagnetic theory, we successfully established a microwave plasma generation system, with the frequency of 2.45GHz, the main mode of TE10, the power of 3kW. The system consists of microwave generation unit, plasma reactor, a vacuum pumping unit, cooling unit and a plasma diagnostic unit. It is one of the few experiment platforms which are to research high-power microwave plasma specifically. The experimental platform can accomplish microwave plasma generation, characteristics and the application research.We use vertical reactor and 45°incline one to study microwave plasma discharge characteristics, and experimental results show that at 1/4 wavelength position of the microwave cavity, electric field reach the maximum and the chamber structure does not affect the excited species, but the spectrum intensity is stronger, which illustrates that the vertical reactor produces a relatively high density of active particles. Under the experimental conditions (100Pa to 1000Pa pressure,150W to 500W), the electron excitation temperature can reach 2eV, the electron temperature can reach 6eV, electron density is above 1017/m3, with the increase of input microwave power and the reduction of pressure, the electron density can even reach 18/m3, which is consistent with the characteristics of surface wave plasma characteristics.On the basis of the research of microwave plasma excitation characteristics, methane reforming is initially researched to produce hydrogen by microwave. There are CH,C,C2,Ha,Hβ,in the products. The relative content of hydrogen is the biggest, and carbonization in the reactor is very serious.